Field of Technology
The invention relates to an HMD apparatus with an imaging optical system for each of the two eyes of a user, which comprises at least one display unit to be viewed by the respective eye, as well as to a device for the acquisition of the viewing direction of at least one eye within a field of view of the display unit using an eye camera.
Brief Discussion of Related Art
So-called HMD [Head-Mounted Display] apparatuses are caps that can be placed on the head and that have two small monitor screens each of which is viewed with one eye of the user. Onto these monitor screens, a real or virtual environment is projected taking into consideration the different viewing angles of the two eyes. Furthermore, position changes of the HMD apparatuses are acquired, so that the represented image is changed accordingly. For example, when the user turns his/her head, the corresponding image is represented in this real or virtual direction. More recent HMD apparatuses, as disclosed in U.S. Pat. No. 6,433,760, for example, moreover acquire the eye movements of the user (so-called eye tracking system), in order to change, on the basis of this, the represented image analogously to the head movement toward the viewing direction relative to the head. The acquisition of the eye position or eye movement can occur by means of a camera that looks at an eye, wherein it is preferable for the position of the pupil to be determined by image processing. For this purpose, the eye is illuminated with infrared light, to which the camera is sensitive.
For an optimal position acquisition of the position of the eye, the camera has to acquire the entire eye, wherein the pupil representation in the “forward viewing” has to be as much in the center of the image section of the camera as possible. If an HMD apparatus with an eye tracking apparatus is used by only one person, an individual adaptation of the camera viewing direction can occur a single time, so that the required adjustment effort is not essential. On the other hand, if such an HMD apparatus is used by changing users having necessarily different facial features, such as distance between the eyes, nose and cheek shape, etc., then the rapid adaptation of the eye camera represents a problem.